434 SUMMARY OF CURRENT RESEARCHES RELATING TO 



form may also repeat itself through a number of generations. The 

 zoospores of the endophytic protococcus-like form germinate after 

 coming to rest, on the surface of the Lemna, and give rise to the 

 stigeoclonium-like epiphytic form. This produces macrozoospores, 

 with four cilia, which continue to repeat the same form, and micro- 

 zoospores, which sometimes, without conjugation, either enter the 

 air-cavities beneath the stomata, and develope the endophytic form, or 

 repeat the epiphytic form on the surface of the host : at other times 

 they conjugate, and the zygozoospore also probably enters the air- 

 cavities and gives rise to the endophytic form. 



When cultivated in a moist atmosphere the cells of the epiphytic 

 form increase in size and multiply rapidly, and, like the microzoospores 

 and macrozoospores, may pass into a resting condition, their cell- wall 

 thickening, but without any formation of jelly. The apical cells of 

 the filaments finally put out long apical points destitute of chloro- 

 phyll. 



Both kinds of zoospore have a red eye-spot, and are formed by 

 repeated bipartition, with the exception of the macrospores, which 

 are produced singly in the sporangia. The macrospores are 13 • 5 /u, 

 long and 10 fx broad, and provided with four cilia; the micro- 

 spores are biciliated, and 7" 5 /a long by 3-5 broad. The endophytic 

 form produces zoospores of one kind only, resembling the micro- 

 zoospores. 



The parasite occurs especially on the white dead parts of the 

 Lemna, where it produces dark green spots visible to the naked eye. 



Godlewskia, a new Genus of Cryptophyceae.* — E. de Janczewski 

 has found, growing on Batrachospermum in a ditch near the botanic 

 garden of Cracow, a new species and genus of algse, to which he gives 

 the name Godlewskia aggregata. It is distinguished at a glance from 

 its host by its beautiful blue-green colour. Each individual consists 

 of a basal flask-shaped cell or sterigma, and a number of smaller 

 globular cells, borne in a row at its apex, conidia, formed by con- 

 tinued division of the sterigma. These conidia germinate directly, 

 but do not separate easily from the parent sterigma, sometimes as 

 many as two generations being found still attached to it, each basal 

 conidium developing into a sterigma. GodlewsJcia must be assigned 

 to the family Chamsesiphonese among Cryptophyceae. 



Sexuality in Zygnemaceae.f— A. W. Bennett has investigated 

 the reproduction of the Zygnemaceae, with a view to the solution of 

 the question : — Is it of a sexual character ? De Bary, twenty-five 

 years ago, and since then, Wittrock, have instanced what they have 

 thought to be sexual differences between the conjugating cells, though 

 most later writers rather ignore any essential physiological distinction. 

 Mr. Bennett has directed his investigations chiefly to the genera 

 Spirogyra and Zygnema, and from these he supports the inference of 

 the above-mentioned authors. He finds there is an appreciable 



* Ann. Sci. Nat. (Bot.), xvi. (1883) pp. 227-30 (1 pi.). 

 t Journ. Linn. Soc. (Bot.), xx. (1884) pp. 430-9. 



